I know your Joseph Curtis family of Onondaga but I don't know if there is a connection between your family and mine.
John and Thomas Curtis lived in Claradon Twp., Rutland Co., Vermont. Thomas first bought property there in 1774 and was last found there about 1782. Thomas went to Canada via Onondaga...he is not in Canada until about 1800...but I can't trace him in those 20 yrs.
John Curtis and his brother Comfort Curtis, who lived in White Creek, New York (which is on the border of N.Y and Vermont, and at one time may have been Vermont territory) supported the British and were proscribed. I believe John died in Vermont between 1777-1779. Comfort did go to Canada too but returned to White Creek, where he died in 1817.
John and Comfort were the sons of John Curtis and Margaret Davis, they were born in Stonnington, Conn. but had been living in Rhode Island before moving to Vermont. I think Thomas may be a cousin....I have not been able to identify his parents. My best guess is that he is son of Stephen Curtis who is a half brother to John and Comfort.
In Clarendon at the same time as John, Comfort and Thomas is the family of Thadius Curtis. I don't know whether there is aconnection or not.Would be interested to know.